When you buy software on a DVD, you own the software, at least until you install it and go through the clickwrap agreement that revokes your ownership. With enough lawyers, you could probably poke some holes in that clickwrap agreement anyway. But they probably have more lawyers than you.

In the olden days, we installed software by copying it off floppy disks onto our hard drives. There was no clickwrap agreement, because there was no installer. We owned that software.

GOG advertises that purchasers own the software they buy. www.gog.com/en/news/welcome_to_gog

Lots of open source software can be owned. You have to do something that grants you ownership in the first place, like buying it on a disc. Downloading it for free might or might not, I don’t know. But no FOSS license I know of has any clause that revokes ownership. The GPLv2 has a specific clause that says

You are not required to accept this License

so you can always choose to reject the whole GPL, and revert back to the implicit rules of commerce, “Pay money, receive thing” which confers ownership.